a) Field of the Invention
The present invention relates to a combined lancet and multi-function cap (or tip) of the disposable type, for use in obtaining blood samples for diagnostic purposes.
The invention also relates to an improved blood sampling device also known in the trade as a "lancet injector" or "lancing device", that can be used with the combined lancet and multi-function cap according to the invention for obtaining required blood samples in a very safe and accurate manner.
b) Brief Description of the Prior Art
Lancets are well known devices commonly used in the medical field to make small punctures in a patient's skin in order to obtain small samples of blood. Lancets usually comprise an elongated plastic body from which projects a sharpened metal needle covered by a protective cap that is removed before use of the needle to puncture the skin (see, by way of non-restrictive example, U.S. Pat. No. 3,358,689 to HIGGINS).
Lancet injectors are also well known devices that are used to "fire" or project a lancet toward the skin of a patient in order to puncture the same in an accurate, standardized and consistent manner.
Such devices have originally been devised for use by the patients' themselves, who have to puncture their own skin on a regular basis and are afraid or reluctant to do so "manually". However, they are now commonly used by professional medical staff, essentially because they make the duration and depth of penetration of the lancet needle through the skin very short and small and serve to shield the patient from viewing the actual skin piercing act, and thus they minimize pain and trauma associated with the process.
In the recent years, numerous patents have been granted on lancet injectors of different and improved structures. By way of non-restrictive examples, references can be made to the following U.S. Pat. Nos. 4,139,011 to BENOIT et al, 4,449,529 to BURNS et al, 4,469,110 to SUAMA, 4,527,561 to BURNS, 4,677,979 to BURNS, 4,738,261 to ENSTROM, 4,889,117 to STEVENS, 4,895,147 to BODICKY et al, 4,976,724 to NIETO et al, 4,990,154 to BROWN et al, 5,074,872 to BROWN et al.
A brief review of these patents shows that all the known lancet injectors use metallic coil or leaf springs to push the lancet forward upon actuation and then retract it immediately in order to minimize pain sensation (see, for example, U.S. Pat. Nos. 4,203,446; 4,469,529; 4,527,561; 4,677,979 and 4,889,117).
Some known lancet injectors are also provided with means, usually in the form of a screwable ring or separable multiple sized adaptor caps, to control and adjust the depth of penetration of the needle of the lancet (see, for example, U.S. Pat. Nos. 4,469,110 and 4,895,147).
Some other known lancet injectors are provided with means for allowing ejection of the lancet after use without having to seize it with the fingers to do so. Such is achieved either by use of mechanical ejecting means (see U.S. Pat. No. 4,976,724) or by use of a separate disposable isolation cap operatively connected to the lancet in such a manner as to act as a protective hood for its needle (see U.S. Pat. Nos. 4,990,154 and 5,074,872). The basic idea behind this last generation of lancet injectors is essentially to make them safer in use by the professional medical staffs who are more and more concerned with the risk of disease transmission in the case of accidental puncture with a used lancet and resultant exposure to contamination through the trace of blood left on the used lancet.